Add KPI to WPA after loading etl file

Question

Hi,
I want to analyze build process of the c++ project in order to make choice which headers to precompile and use accordingly to improve build process timing and performance.
When I open etl file(collected using pattern <vcperf start mysess - start_build - wait_build_to_finish - vcperf stop mysess etlfile>) in WPA I cant find any file information, e.g. missing diagnostic KPI which possibly can include header informations. So, I am kindly asking for an advice how to add KPI to WPA or to vcperf.

Thanks